The present invention relates generally to a gas cooling and washing apparatus and more particular a dip-type or immersion cooler for cooling and washing for example dust-laden hot gas which is flowing possible under an elevated pressure.
A dip-type or immersion cooler for cooling and washing a dust-laden flowing gas is disclosed for example in German published application (DE-AS) No. 11 57 585, comprising a dip pipe which has a fluid-wetted coaxial venturi passage and which extends vertically into a container with washing fluid, with a coaxial gas feed pipe at the intake of the venturi passage and a protective tube concentrically surrounding the gas feed pipe in the region of the intake. That arrangement has an overflow channel for the supply of washing fluid to the venturi tube, the intake portion of the venturi tube corresponding to a funnel member which is open in an upward direction. The walls of the intake portion are wetted by a thin film of fluid without any gap therein. To provide the flow of scrubbing fluid into the mouth of the intake portion of the venturi tube, the edge of the intake portion is surrounded by the above-mentioned overflow channel in which the washing fluid, being in that case water, flows in a pressure-less condition. The fluid thus passes in the form of a thin layer over the edge of the channel and into the intake portion. The venturi tube is disposed vertically and the gas to be washed or scrubbed flows downwardly therethrough, the mouth or diffuser of the venturi tube terminating in a separation chamber which is filled with the washing fluid. The gas that flows down into the washing fluid through the venturi tube is distributed in the fluid and issues therefrom, subsequently to be sucked away in the upper part of the chamber by way of gas outlet connections. As the dust-laden gas passes through the washing fluid, the dust is removed from the gas which is cooled at the same time. The dust is deposited on the bottom of the separation chamber and can thus be removed therefrom.
The inlet opening for the gas in the above-described apparatus is in the form of a tubular connecting member which terminates at the axial height of the upper edge of the intake portion of the venturi tube. At the same time, the tubular connecting member is surrounded concentrically by a protective tube which corresponds in diameter to the diameter of the upper edge of the intake portion of the venturi tube while its edge is only spaced from said edge of the intake portion of the venturi tube in such a way as to form a gap or slit, so that the wetting fluid can pass therethrough from the overflow channel and can cover the intake portion of the venturi tube. The conical or funnel-like configuration of the intake portion of the venturi tube provides at the same time that the wall or veil of washing fluid which, being directed downwardly, is accelerated by the force of gravity, can wet the intake portion without leaving any gaps in the film of fluid because, as a result of the conical configuration of the intake portion, the respective surface portions to be wetted by the fluid become progressively smaller in proportion to increasing depth of penetration of the wetting fluid down into the intake portion.
However, operating experience with the above-discussed venturi-type washer or scrubber has shown that, when handling hot gases, the hot gases tend to form caked-on deposits on the walls of the dip pipeor venturi tube, where they come into contact with the washing or wetting fluid. Such deposits are often found to grow very quickly so that the apparatus has to be taken out of operation and cleaned after short periods of operation, with the result that the apparatus is not suitable for washing and cooling dust-laden gas at elevated temperature.